Methanosarcina barkeri DSM-804, a methanogenic bacterium, when exposed to microwave radiation of frequencies ranging from 13.5 to 36.5 GHz, showed faster growth in comparison to the unirradiated bacterial culture. Methane concentration in the biogas generated from the irradiated culture was higher than that from unirradiated one, which was to 76.3% on the 15th day of incubation at a microwave radiation frequency of 31.5 GHz, 10 dbm power when irradiated for 2 h. Microscopic study of pure culture revealed that the cells of M. barkeri were more in number and their cell diameter was enlarged by 20%. Inoculation of the culture in a biogas digester containing a combination of jute waste and vegetable market waste as substrate increased the efficacy of biomethanation and reduced its lag phase significantly. (c) 2005 Elsevier Ltd. All rights reserved.